1. Field of the Invention
The following disclosure generally relates to a communication system, a transmission terminal, a communication method, and a medium.
2. Description of the Related Art
As the infrastructure of network environments improves, devices communicating via networks are used more widely. For example, in a video-conference system, transmission devices that are placed at respective remote locations can execute a remote conference via a communication network such as the Internet. Also, there is a system in which devices called electronic blackboards, which are placed at different sites, communicate via a network to transmit display contents on displays of the electronic blackboards with each other, and to share the display contents (conveniently, referred to as the “electronic blackboard system” below).
Moreover, if users use such distinctive systems at the same time, it is expected that higher-level communication can be made among the users at remote locations.
Incidentally, it is often the case that devices for communication via networks need to be authenticated by a server or a partner device to secure the safety of the communication. However, the authentication needs to be done for each system. Therefore, a user who uses a video-conference system and an electronic blackboard system needs to have his/her device authenticated separately for each of the systems. Therefore, if the user uses the video-conference system while using the electronic blackboard system, the user needs to do authentication operations twice, which incurs a load on the user.
A technology to reduce such an operational load has been devised (see, for example, Japanese Laid-open Patent Publication No. 2010-87704). The Patent Publication discloses a server that, while multiple communication terminals communicate by a first communication unit, if the server receives a communication request from a first communication terminal to a second communication terminal by a second communication unit, obtains connection information of the second communication terminal in the first communication unit; obtains connection information of the second communication terminal in the second communication unit that corresponds to the connection information of the second communication terminal in the first communication unit; and executes communication between the first communication terminal and the second communication terminal by the second communication unit.
However, the technology described in the Patent Publication has a problem that the user needs to store in advance connection information for each communication unit of a communication terminal in a database on the server before starting the communication.
In view of the above, it is a general object of at least one embodiment to provide a communication system that can reduce the user's load when starting communication between devices via a network.